Types of Wood Finishes Used for Woodturning

I use three different types of wood finishes for my turned work.  The function of the piece determines which finish I use.  I make pieces used for display and utility, thus the finish has to meet the needs of those purposes.  Recently I have begun experimenting with paint to develop other decorative effects.  Although, as a general rule, I do not use coloration (other than a limited amount of ebonizing) on my turned work.

Utility or Functional Turnings

I consider utility pieces to be any turnings exposed to repetitive usage.  They require a durable food safe wood finish that can be reapplied easily.  A salad bowl finish is a good example of wood finish for these items.  Traditionally these types of wood finishes have been wiping oils.  Specifically, mineral oil for woodwork, raw oils (i.e. Tung, linseed, olive, walnut, grapeseed, etc.), Tung oil finish, Danish oil, and Boiled Linseed Oil, etc. 
I prefer Mike Mahoney’s Walnut oil finish and his oil wax finish.  This walnut oil is a natural penetrating oil that soaks into the grain and hardens as it dries.  It does not evaporate like other food safe-finishes (i.e. mineral oil) so it requires less reapplication over time.  The oil wax finish is a blend of walnut oil, beeswax, and carnauba wax that provide additional protection and luster to the piece.  The combination of these two produces produces a satin sheen.  A satin sheen is more desirable as it diminishes the effects of wear and age.

What is Food Safe?

There are two schools of thought regarding food safe wood finish.  The first is that any finish once cured is food safe.  The other is that no finish that contains driers, solvents, petrochemicals, etc. is food safe.  Consequently, the later excludes nearly all wood finishes other than raw oils.
The draw back with raw oils is that they cure extremely slowly.  Additionally, they develop only minimal surface build.  The only way to improve cure rates and surface build is to heat treat the oil or to add chemical driers.  Chemical driers are most often heavy metal salts, mainly of chromium or manganese.  Several popular types of commercial wiping finishes have both driers and solvents, thus creating the dilemma.
I personally do not know the accurate answer as to what is a food safe wood finish.  Therefor, I opt avoid the argument altogether and use Mahoney’s Walnut Oil.  This way the finish is completely organic and it has been heat treated to improve the curing qualities.  Supposedly it is a high acid oil which I think may help the cure rates and surface build. 

Sculptural Turnings

I use two types of wood finishes on the cremation urns and hollow forms I make.  Display items by their nature usually do not need to be repaired/refinished.  Nor do they need to be food-safe, and tend to have more shine.  Thus, the amount of gloss on display work determines the finish used.  I produce an ultra-high gloss, a semi-gloss, and a satin sheen on my hollow forms.  Cremation urns are only produced with a satin sheen.
To produce the ultra-gloss and the semi-gloss I use multiple coats of lacquer to build up sufficient surface thickness.  Those items are rubbed out to the desired level of gloss and tactile quality.  Lacquer (nitrocellulose) is a clear and durable finish, it provides good protection and shows the natural contrast of the wood. 
Danish oil, which I mix, is used on hollow forms, cremation urns, and some decorative bowls for a satin finish.  Danish oil is easy to apply, provides good protection, and does not require as many coats as lacquered hollows.  Additionally, I also use automotive wax for ultra-gloss items or paste wax (Mylands) for semi-gloss and satin pieces for additional protection.

Furniture Work

Unlike turned work, I do use stains for furniture pieces occasionally.  I typically use an oil-based stain, or analine dye (both water and alcohol soluble dyes) to bring extra color to the piece.  Except for custom orders, where the customer has specified the color, my preference is to use a colorant tone similar to the natural wood tones of the piece.  I like to let the natural color and patina develop in a piece of furniture.
I use coloration to even out tonal variations in the wood.  Additionally, furniture is often made of boards from different trees often with different tones.  Coloration helps even out those variations across the whole piece.
For top coats I use several types of wood finishes.  I have most often used Danish Oil, Polyurethane, Lacquer, and Shellac depending on the function of the item.  Danish oil and Shellac I gravitate to most often, as I like to build finishes.  Although, I will use either Polyurethane or Lacquer if the function of the furniture requires greater protection or moisture resistance.  Table tops are a good example in those cases.  In recent years I have tended not to use polyurethane as much due to its difficulty to repair.